Generally, a compressor is for changing a mechanical energy into a compressed energy of compressive fluid, and the compressor can be divided into reciprocating type, scroll type, centrifugal type, and vane type compressors.
The reciprocating compressor can be divided into a type in which a driving axis is coupled to an armature of a rotary type driving motor and rotating movements of the driving axis is changed into linear movements of a piston to compress gas, and a type in which a piston instead of the driving axis is coupled to the armature of a reciprocating motor performing linear movements and the piston undergoes the linear reciprocating movements to compress refrigerant.
FIG. 1 is showing an example of the latter reciprocating compressor between above two types.
As shown therein, the conventional reciprocating compressor comprises a compression unit C installed inside a casing V, in which oil is filled on the bottom therein, in a transverse direction for sucking, compressing, and discharging the refrigerant, and an oil feeder O fixed on outer side of the compression unit C for providing a sliding portion with oil.
The compression unit C comprises a frame 1 of annular shape; a cover 2 fixed on one side surface of the frame 1; a cylinder 3 fixed on a center part of the frame 1 in a transverse direction; an inner stator 4A fixed on an outer circumferential surface of the frame 1 supporting the cylinder 3; an outer stator 4B fixedly installed on an outer circumferential surface of the inner stator 4A with a predetermined air gap for forming induced magnetism with the inner stator 4A; an armature 5 disposed on the air gap between the inner and outer stators for performing linear reciprocating movements; a piston 6 fixed integrally on the armature 5 for sucking and compressing refrigerant gas as sliding in the cylinder 3; and an inner resonant spring 7A and an outer resonant spring 7B for inducing the armature 5 to perform the resonant movements on the air gap between the inner/outer stators continuously.
On the other hand, as shown in FIG. 2, the inner stator 4A is formed as a hollow cylinder in which a plurality of stator cores 4a are laminated as one by one or as bunches, and an inner circumferential surface thereof is press-fitted into the outer circumferential surface of the frame 1, that is, the outer circumferential surface of a boss portion 1a in which the cylinder is inserted.
Unexplained reference numeral 8 represents a discharge valve, and 9 represents a suction pipe.
The conventional reciprocating compressor as constructed above is operated as follows.
That is, when an electric current is applied to the stator in the reciprocating compressor comprising the inner stator 4A and the outer stator 4B to generate the induced magnetism, the armature 5 disposed between the above stators undergoes linear reciprocating movements by the inner/outer resonant springs 7A and 7B and the piston 6 undergoes linear reciprocating movements inside the cylinder 3. In addition, according to that the piston 6 undergoes the linear reciprocating movements inside the cylinder 3, the refrigerant gas flowing into the casing V is compressed inside the cylinder and is discharged as pushing a discharge valve assembly 8.
However, in the above inner stator fixing structure of the conventional reciprocating compressor, the inner stator is formed by laminating thin stator cores in a radial direction to be a hollow cylinder shape and one side end of the laminated inner stator is put into the frame to be contacted to the outer circumferential surface of the boss portion for cylinder insertion. Therefore, the inner stator scratches the outer circumferential surface of the boss portion for cylinder insertion on the frame to generate burr. In addition, the burr is induced into the compression chamber with the oil filled in the casing and attached to the valve, and the opening/closing operations of the valve are not made smoothly. Otherwise, the burr is induced into the sliding portion, and therefore, abrasion on the cylinder or piston performing the linear reciprocating movements.
Also, the outer circumferential surface of the boss portion on the frame is worn by the scratches, and accordingly, the inner stator is loosen and the vibration noise of the compressor is also increased.